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CVE-2021-43539

HIGH
8.8
CVSS Score
Published: December 8, 2021 at 09:20 PM UTC
Updated: June 17, 2026 at 04:11 AM UTC
4 products affected across 2 vendorsDebian LinuxFirefoxThunderbird

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Severity
HIGH8.8
Exploit prediction
EPSS 2%

Description

Failure to correctly record the location of live pointers across wasm instance calls resulted in a GC occurring within the call not tracing those live pointers. This could have led to a use-after-free causing a potentially exploitable crash. This vulnerability affects Thunderbird < 91.4.0, Firefox ESR < 91.4.0, and Firefox < 95.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Debian Linux· Debiandrupal
95%
10.011.09.0
Firefox· Mozilla
95%
v < 95
Affected range stops below 95, so it looks safe — our inference, not a vendor statement
Affected range stops below 95.0, so it looks safe — our inference, not a vendor statement
Firefox ESR· Mozilla
95%
v < 91.4.0
Affected range stops below 91.4.0, so it looks safe — our inference, not a vendor statement
Thunderbird· Mozilla
95%
v < 91.4.0
Affected range stops below 91.4.0, so it looks safe — our inference, not a vendor statement

References (10)

x_refsource_MISCIssue TrackingPermissions RequiredVendor Advisory
Source: [email protected]
https://bugzilla.mozilla.org/show_bug.cgi?id=1739683
Mailing Listx_refsource_MLISTThird Party Advisory
Source: [email protected]
https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html
Mailing Listx_refsource_MLISTThird Party Advisory
Source: [email protected]
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202202-03
Vendor Advisoryx_refsource_GENTOOThird Party Advisory
Source: [email protected]
https://security.gentoo.org/glsa/202208-14
Vendor Advisoryx_refsource_DEBIANThird Party Advisory
Source: [email protected]
https://www.debian.org/security/2021/dsa-5026
Vendor Advisoryx_refsource_DEBIANThird Party Advisory
Source: [email protected]
https://www.debian.org/security/2022/dsa-5034
x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.mozilla.org/security/advisories/mfsa2021-52/

CVSS

8.8HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-416

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